372 research outputs found
Forage selection preferences of experienced cows and naïve heifers grazing native tallgrass range during winter
Beef Cattle Research, 2011 is known as Cattlemen’s Day, 2011Estimating the nutritive value of a grazing animal’s diet is a significant challenge.
Description of the botanical composition of a grazed diet is vital in that regard. Microhistological
analysis of fecal material has been used for estimating the botanical composition
of wild and domestic ungulate diets since first described by Baumgartner and
Martin in 1939.
Little research has been conducted on the diet selection preferences of multiparous beef
cows compared to primiparous beef cows. We hypothesized that foraging strategies
change as cows age. To that end, our objective was to characterize differences in diet
selection between experienced multiparous and naïve primiparous beef cows grazing
dormant, native tallgrass pastures during winter
The effect of timing of oral meloxicam administration on physiological responses in calves after cautery dehorning with local anesthesia.
Abstract Dehorning is a painful husbandry procedure that is commonly performed in dairy calves. Parenteral meloxicam combined with local anesthesia mitigates the physiological and behavioral effects of dehorning in calves. The purpose of this study was to determine the influence of timing of oral meloxicam administration on physiological responses in calves after dehorning. Thirty Holstein bull calves, 8 to 10 wk of age (28–70kg), were randomly assigned to 1 of 3 treatment groups: placebo-treated control group (n=10), calves receiving meloxicam administered orally (1 mg/kg) in powdered milk replacer 12h before cautery dehorning (MEL-PRE; n=10), and calves receiving meloxicam administered as an oral bolus (1 mg/kg) at the time of dehorning (MEL-POST; n=10). Following cautery dehorning, blood samples were collected to measure cortisol, substance P (SP), haptoglobin, ex vivo prostaglandin E 2 (PgE 2 ) production after lipopolysaccharide stimulation and meloxicam concentrations. Maximum ocular temperature and mechanical nociceptive threshold (MNT) were also assessed. Data were analyzed using noncompartmental pharmacokinetic analysis and repeated measures ANOVA models. Mean peak meloxicam concentrations were 3.61±0 0.21 and 3.27±0.14μg/mL with average elimination half-lives of 38.62±5.87 and 35.81±6.26h for MEL-PRE and MEL-POST, respectively. Serum cortisol concentrations were lower in meloxicam-treated calves compared with control calves at 4h postdehorning. Substance P concentrations were significantly higher in control calves compared with meloxicam-treated calves at 120h after dehorning. Prostaglandin E 2 concentrations were lower in meloxicam-treated calves compared with control calves. Mechanical nociceptive threshold was higher in control calves at 1h after dehorning, but meloxicam-treated calves tended to have a higher MNT at 6h after dehorning. No effect of timing of meloxicam administration on serum cortisol concentrations, SP concentrations, haptoglobin concentrations, maximum ocular temperature, or MNT was observed. However, PgE 2 concentrations in MEL-PRE calves were similar to control calves after 12h postdehorning, whereas MEL-POST calves had lower PgE 2 concentrations for 3 d postdehorning. These findings support that meloxicam reduced cortisol, SP, and PgE 2 after dehorning, but only PgE 2 production was significantly affected by the timing of meloxicam administration
Superconductivity in the two dimensional Hubbard Model.
Quasiparticle bands of the two-dimensional Hubbard model are calculated using
the Roth two-pole approximation to the one particle Green's function. Excellent
agreement is obtained with recent Monte Carlo calculations, including an
anomalous volume of the Fermi surface near half-filling, which can possibly be
explained in terms of a breakdown of Fermi liquid theory. The calculated bands
are very flat around the (pi,0) points of the Brillouin zone in agreement with
photoemission measurements of cuprate superconductors. With doping there is a
shift in spectral weight from the upper band to the lower band. The Roth method
is extended to deal with superconductivity within a four-pole approximation
allowing electron-hole mixing. It is shown that triplet p-wave pairing never
occurs. Singlet d_{x^2-y^2}-wave pairing is strongly favoured and optimal
doping occurs when the van Hove singularity, corresponding to the flat band
part, lies at the Fermi level. Nearest neighbour antiferromagnetic correlations
play an important role in flattening the bands near the Fermi level and in
favouring superconductivity. However the mechanism for superconductivity is a
local one, in contrast to spin fluctuation exchange models. For reasonable
values of the hopping parameter the transition temperature T_c is in the range
10-100K. The optimum doping delta_c lies between 0.14 and 0.25, depending on
the ratio U/t. The gap equation has a BCS-like form and (2*Delta_{max})/(kT_c)
~ 4.Comment: REVTeX, 35 pages, including 19 PostScript figures numbered 1a to 11.
Uses epsf.sty (included). Everything in uuencoded gz-compressed .tar file,
(self-unpacking, see header). Submitted to Phys. Rev. B (24-2-95
Sum rules and dualities for generalized parton distributions: is there a holographic principle?
To leading order approximation, the physical content of generalized parton
distributions (GPDs) that is accessible in deep virtual electroproduction of
photons or mesons is contained in their value on the cross-over trajectory.
This trajectory separates the t-channel and s-channel dominated GPD regions.
The underlying Lorentz covariance implies correspondence between these two
regions through their relation to GPDs on the cross-over trajectory. This point
of view leads to a family of GPD sum rules which are a quark analogue of finite
energy sum rules and it guides us to a new phenomenological GPD concept. As an
example, we discuss the constraints from the JLab/Hall A data on the dominant
u-quark GPD H. The question arises whether GPDs are governed by some kind of
holographic principle.Comment: 45 pages, 4 figures, Sect. 2 reorganized for clarity. Typos in Eq.
(20) corrected. 4 new refs. Matches published versio
Ginzburg-Landau functional for nearly antiferromagnetic perfect and disordered Kondo lattices
Interplay between Kondo effect and trends to antiferromagnetic and spin glass
ordering in perfect and disordered bipartite Kondo lattices is considered.
Ginzburg-Landau equation is derived from the microscopic effective action
written in three mode representation (Kondo screening, antiferromagnetic
correlations and spin liquid correlations). The problem of local constraint is
resolved by means of Popov-Fedotov representation for localized spin operators.
It is shown that the Kondo screening enhances the trend to a spin liquid
crossover and suppresses antiferromagnetic ordering in perfect Kondo lattices
and spin glass ordering in doped Kondo lattices. The modified Doniach's diagram
is constructed, and possibilities of going beyond the mean field approximation
are discussed.Comment: 18 pages, RevTeX, 7 EPS figures include
Choice of tracers for the evaluation of spray deposits
Tracer substances, used to evaluate spraying effectiveness, ordinarily modify the surface tension of aqueous solutions. This study aimed to establish a method of using tracers to evaluate distribution and amount of spray deposits, adjusted to the surface tension of the spraying solution. The following products were tested: 0.15% Brilliant Blue, 0.15% Saturn Yellow in 0.015% Vixilperse lignosulfonate, and 0.005% sodium fluorescein, and mixtures of Brilliant Blue plus Saturn Yellow and Brilliant Blue plus sodium fluorescein at the same concentrations. Solutions were deposited on citrus leaves and stability was determined by measuring fluorescence and optical density of solutions without drying, dried in the dark and exposed to sunlight for 2, 4 and 8 h. These values were compared to those obtained directly in water. The static surface tension of the tracer solution was determined by weighing droplets formed during a period of 20 to 40 seconds. The Brilliant Blue and Saturn Yellow mixture at 0.15% was stable under all conditions tested. It was not absorbed by the leaves and maintained the same surface tension as that of water, thus permitting concentration adjustment to the same levels used for agrochemical products, and allowing the development of a qualitative method based on visual evaluation of the distribution of the pigment under ultraviolet light and of a quantitative method based on the determination of the amount of the dye deposited in the same solution. Spray deposition could be evaluated at different surface tensions of the spraying solution, simulating the effect of agrochemical formulations
Origins of the Ambient Solar Wind: Implications for Space Weather
The Sun's outer atmosphere is heated to temperatures of millions of degrees,
and solar plasma flows out into interplanetary space at supersonic speeds. This
paper reviews our current understanding of these interrelated problems: coronal
heating and the acceleration of the ambient solar wind. We also discuss where
the community stands in its ability to forecast how variations in the solar
wind (i.e., fast and slow wind streams) impact the Earth. Although the last few
decades have seen significant progress in observations and modeling, we still
do not have a complete understanding of the relevant physical processes, nor do
we have a quantitatively precise census of which coronal structures contribute
to specific types of solar wind. Fast streams are known to be connected to the
central regions of large coronal holes. Slow streams, however, appear to come
from a wide range of sources, including streamers, pseudostreamers, coronal
loops, active regions, and coronal hole boundaries. Complicating our
understanding even more is the fact that processes such as turbulence,
stream-stream interactions, and Coulomb collisions can make it difficult to
unambiguously map a parcel measured at 1 AU back down to its coronal source. We
also review recent progress -- in theoretical modeling, observational data
analysis, and forecasting techniques that sit at the interface between data and
theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue
connected with a 2016 ISSI workshop on "The Scientific Foundations of Space
Weather." 44 pages, 9 figure
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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